The /proc Filesystem

If you need to gather information about the processes running on your
machine, you can use the /proc filesystem.
Although there's a section about it in the
Processes chapter of the
QNX NeutrinoProgrammer's Guide,
this filesystem isn't understood very well.
This appendix describes the main features of the /proc filesystem
so you can use it in your own utilities.

First of all, the /proc filesystem is a virtual filesystem — it doesn't actually exist
on disk; it exists only as a figment of the process manager's imagination.

The /proc filesystem contains a number of entities:

directories, one per process, for every process running in the system

the boot subdirectory — a mini filesystem that contains the files from the startup image

the (hidden) mount subdirectory.

Our main focus in this chapter is the first item, the directories describing each process in the system.
We'll describe the functions available to get information about the processes (and their threads).

For completeness, however, we'll just briefly mention the other two items.